In the stacking of boards, a whole layer of boards is laid on the top of a board stack which is under construction by means of an off-loader which moves transversely of the longitudinal direction of the boards to a position in over the board stack. There, the layer of boards is off-loaded on subjacent spacer sticks whose longitudinal directions are transversely directed in relation to the longitudinal direction of the boards. Thus, the off-loader is placed along one longitudinal side of the board stack which is being constructed.
The board stack which is being built up is placed on a vertically adjustable substrate which is gradually lowered as the height of the board stack increases so that the level of the uppermost layer in the board stack is thereby throughout substantially unchanged.
For placing spacer sticks on the upper side of a recently off-loaded layer of boards, use is normally made of two chains which run in over the stack and in its longitudinal direction, and in parallel with one another, and at such a height over the stack that the off-loader can pass under them for off-loading a layer of boards. The chains have hooks which, on the lower parts of the chains, are rearwardly open in the direction of travel. The chains are employed for conveying spacer sticks from a feeder device to positions over the stack. By the employment of vertically movable abutments, the spacer sticks are caused to release from the hooks and fall down on the upper side of the stack.
A spacer stick layer device of this type comprises a considerable quantity of complex mechanical machinery. The distances between adjacent spacer sticks cannot readily be changed, and nor can spacer sticks of varying dimensions be handled. Finally, the work rate is too low.
For laying out spacer sticks, an apparatus is further known in the art by means of which the spacer sticks are placed out on a substrate on the opposite side of the board stack in relation to the off-loader and from thence are lifted and displaced by means of suitable gripping members in over the board stack where the spacer sticks are lowered and deposited on the board stack.
An apparatus of this type operates slowly because of the long transport distances which are required on laying out the spacer sticks. Further, it is difficult to get at the finished stack, since it is surrounded by machinery.